Hydraulic transmission control



Feb. 7, 1939. E. o. S CHJOLIN HYDRAULIC TRANSMISSION CONTROL Filed June 19, 1937 I5 Sheets-Sheet 1 I75 I69 ll/ Feb. 7, 1939. E. o. SCHJOLIN HYDRAULIC TRANSMISSION CONTROL 3 Sheets-Sheet 2 Filed June 19, 1937 3mm saw/16 Sc/yb/zh HYDRAULI C TRANSMI S S I ON CONTROL Filed June 19, 1937 3 Sheets-Sheet 3 lD TATES PATE r: RAULIC TRANSMSSION CONTROL Eric lle Schjolin, Pontiac, Mich, assignor to General Motors (lorporation, Detroit, Mich, a corporation of Delaware Application June 19, 1937, Serial No. 149,139

' 1 Claim. (oi. 74-346) This invention relates to a control for change from the drivers compartment, it is being shown speed mechanism and has been designed more on the drawings as applied to a motor vehicle particularly for those motor vehicle installations having its power plant located over the rear axle. where the change speed mechanism is located at The specific details of the power plant are not some considerable distance from the operators important but for the purpose of illustration compartment. there is shown an engine 35, a transmission An object of the invention is to provide a simchange speed gearing 3i and a clutch housing 3Q plified form of device for making the several arranged in series above the rear axle ii. The ratio changes by the use of a single lever. engine shaft is not shown but it extends through in A further object is to provide for ratio changes the change speed box 3i and into clutch housing lay-mechanism utilizing a movable column of fluid 39. The shaft driven by the clutch is not shown for shifting the conventional rails and gears and but it extends forwardly and into housing 3'5 an electro-magnet for selecting the rail to be where it is provided with gear :3, as shown in shifted, the switch for so selectingthe rail being Figure 6. The countershaft and its gears are preferably associated with the lever. not illustrated in the drawings. They are con 15 ()ther objects and advantages will be underventional. The output shaft leading forwardly stood from the following description. from the change speed transmission and to a In the drawings accompanying the description, suitable differential mechanism for driving the Figure 1 is a view in side elevation of a motor wheels I3 appears on the drawings and is marked vehicle, the view being broken away to illustrate by numeral 65. Within the gear housing this the invention, This view is from the legt side shaft 45 rotatably'supports a gear t7. Slidable of the vehicle facing toward the front. along the axis of the output shaft is a clutch Figure 2 is a transverse section on a longitudisleeve 59 adapted to be reciprocated toward gear nal plane through that part of the mechanism 63 or gear d! by fork 5i secured to a reciprocable 26 carrying the operating lever. rail 53. When moved toward gear 43 a synchroas Figure 3 is a section on line 3-3 of Figure 1. nizing device 55 of well-known construction first Figure 4 is a section on line 6- of Figure 3. functions in the usual way and then teeth 5? of I Figure 5 is a section on line 5-5 of Figure 6, the sliding clutch member engage teeth 59 rigid and with gear i3 and the input shaft to effect a direct Figure 6 is a section on line 6-6 of Figure 3, drive through the transmission mechanism. 80

this view being seen from' the right side of the When the sliding clutch member 49 is moved tovehicle. 7 ward the gear 4! a similar synchronizing unit 6i Referring to the drawings, numeral ii reprefirst performs its usual function and then clutch sents the motor vehicle as a whole mounted on teeth, not shown, but carried by the sliding clutch rear wheels is and front wheels l5. In the i9 engage clutch teeth 63 formed rigidly with as drivers compartment there will be seen a hand gear 67 whereby gear ll becomes non-rotatably wheel ll for the purpose of steering. Suitably connected to the driven shaft. It is then driven mounted adjacent the steering column is a housfrom gear t3 through the conventional countering l9 within which a lever 2i is pivoted on a shaft gears. This gear train effects a second to horizontal axis 23. The upper end of the lever speed drive. Low and reverse ratios are accom- 49 extends to a position near the steering wheel. plished by a fore and aft reciprocation of a gear The lever has forward and rearward movements 65 slidable on external teeth 61 of the clutch and may be yieldingly held in a mid position by member 39. In one direction the gear 65 is made a detent. The detent comprises a ball 25 pressed to mesh with the countershaft gear for low speed by a spring 27 carried in a cap 29 threaded in a and in the other direction of reciprocation it en- 45 boss M of the housing. The spring pressed ball gages with an'idler gear, the idler being driven engages a notch in an arm 33 formed as a part of by the countershaft. The drive through the idler lever'2i. The forward and rearward movements effects reverse. Gear 65 has a collar 69 which of the lever 2! function to shift forwardly and receives a fork ll carried by a reciprocable rail rearwardly one or the other of the shift rails of i3. 50 the change speed transmission as will be ex- Fork it extends above its rail 53 as at l5 and plained. is provided with a recess to receive a rounded For the reason that the invention is more parextension or pin 11 projecting from an arm l9, ticularly useful in those vehicles where the the latter extending radially from ahub 8i keyed change peed mechanism is quite far removed to a solid shaft 83. Shaft 83 is located within a 81. From hub 81 there extends a radial arm 89 having an axial pin 9I located in the recess of i an upper extension 93 of fork 1I. Shaft 83 is supported in an end bearing 95 formed in a cover 94 of a top housing 91, this housing being secured in any convenient way on the top of the change to reciprocate bodily within chamber I88. Prospeed housing 31. Shaft 85 is rotatably supported within a bearing 99 formed between theends of the top housing or closure 91. To theright of bearing 99 the housing 91 comprises a compartment I88 within which the shafts 83 and 85 are provided with arms IM and I83 respectively. Arms IM and I83 have crankpins I85 and I81 respectively. These pins may be alternately received within recesses I89 and III of a crosshead H3. The crosshead is adapted vision for its bodily movement will be seen from an inspection of Figure 6. The crosshead is also mounted to rotate about an axis in the plane of Figure 6. The pivotal supporting members extend into the ends of a central opening I I5 of the crosshead as will be more particularly explained.

The construction provided for the rotation of the crosshead about its axis is best shown in Figure 6. Diametrically opposite cylinders H1 and H9 extend from compartment I88. Within each cylinder is a piston I2I. The pistons project blocks I23 against opposite faces of the crosshead. Threaded screws I25 project through the pistons and blocks and have coned ends I21 extending into the opposite ends of the aperture II5. It is upon these ends that the crosshead rocks so that either the crankpin I85 of shaft 83 or the pin I81 of shaft 85 may engage the crosshead. It will be understood therefore that the above described bodily movement of the crosshead will rock shaft 83 or shaft 85 dependent upon its tilted position. In the position shown by Figure 3 shaft 85 will be rocked by such bodily movement. Such rocking ofshaft 85 will rock arm 89 and reciprocate rail 13 to positions for low speed or reverse driving. If, on the other hand, crosshead H3 is tilted so that crankpin I85 is engaged in recess I89 the bodily movement of the crosshead will operate to rock shaft 83 and reciprocate rail 53 and make shifts between high speed and second speed, dependent upon whether the crosshead is moved from its neutral position or to the right or left (Figure 6). It may be explained that the gear boxmay use any preferred form of spring detent for the rails and also that any suitable device may be used for locking one rail in its neutral position when the other rail is being shifted. Thisprovision is illustrated in Figure 4 where a ball I29 is pressed by a spring I3I located in a cup I33 threaded into the gear box. There are three notches I35, I31, I39 in the rail 53 for engagement with the ball. Notch I31 is for the neutral position of the rail and notches I35 and I39 are for the extreme positions. Just such an expedient is provided for the other rail as is shown by Figure 4. Between the rails there is a ball I4I located in a housing recess I43 and between notches situated at the neutral position of each rail. If either rail is moved from its neutral position it pushes the ball I43 into the notch of the other rail and thereby looks that rail to the housing.

The means for rocking-the crosshead about the coned ends of the screws I25 includes a solenoid I45 assembled within the chamber I88. This solenoid is adapted to be energized by an electric circuit which includes wires I41, a suitable source of electrical energy, not shown, and a manually operable switch which may, as shown, be located within the upper end of the hand lever 2|.

Figure 2 shows an insulating knob I49 at the upper end of lever 2| through which knob may be projected a circuit closing member I5I normally held outwardly by a spring I53.

Inward movement of I5I against the resistance of the spring causes the member I5I to close the circuit through terminals I55 and I51. When the current is so closed by the switch the solenoid I45 projects a plunger I59 against the crosshead II3 moving the latter to the position shown by Figure 3. During this operation a U-shaped spring I6I is compressed. This spring I6I has a fixed anchor I63 and is engaged with the crosshead at I66. When the circuit is opened the spring I6I is available to rotate the crosshead to its opposite position in which the parts I85 and I89 are engaged. It will be understood from the drawings that this rotation of the crosshead to release one shaft and engage the other by means of the spring and the solenoid can take place only when the pins I85 and I81 are diametrically opposite. Such diametrically opposite arrangement occurs only when the rails 53 and 13 are in their neutral positions, the position shown by Figure 4. It will be seen therefore that the rotation of the crosshead from a position for operating one rail to a position for operating the other rail can be made only when 'both rails are in their neutral positions.

The provision for bodily movement of the crosshead for obtaining the several driving ratios will now be explained.

Referring to Figure 2, the housing I9 is constructed with two co-axial cylinders I65 and I61. Within these cylinders are connected pistons I69 and- I1I each provided with a suitable seal I13. Each cylinder has a closure cap I 15 and within each cylinder a spring I11 is seated against the cap and engages the piston seal. Lever 2I has a lower integral arm I19 engaging between abutments I8I and I83 on the rod connecting the two pistons. The cylinders correspond to master cylinders of the hydraulic brake system. The space I85 above the cylinders serves as a reservoir and the communication between each cylinder and the reservoir is provided by means of an opening I81. A fitting I89 connects cylinder I65 to a conduit I9I. Cylinder .I61 communicates by means of a passage I93 and a fitting I95 with a pipe, I91. Conduit I9I extends to the rear end of the vehicle and is there connected by a suit-- able fitting I99 to the cylinder I I1. Similarly, conduit I91 extends to the cylinder I I9. Each of these cylinders is provided with a conventional air bleeding expedient such as 28I. Within cylinders H1 and H9 the pistons III carry'flexible seals 283. It will be seen that since both pistons I69 and "I are moved simultaneously and in the same direction, fluid is transmitted from one and fluid is admitted to the other of the cylinders H1 and 9 with the result that fore and aft movements of lever 2| move pistons I2I together and in the same direction from the mid-position shown A by Figure 6 and in so doing the crosshead II3 moves with the result that one or the other of the rails is shifted, the low speed and reverse railif the solenoid has been actuated by the button I5 I,

the high-speed and second speed rail 11' the buthousing, a closure for said housing, said closure formed with a first chamber, co-axial rockshatts in said first chamber, arms on said shafts operably connected to said rails, said closure having a second chamber, a second set of arms on said rockshafts within said second chamber, a crosshead bodily movable in said second chamber, opposed cylinders formed as a part of said closure. pistons in said cylinders, means projecting from said pistons to bodily move and to pivotally support said crosshead, mechanism to rock said crosshead to engage the one or the other of said second arms, a second pair of opposed cylinders having pistons therein, manually operable means to move said second pistons, liquid carrying conduits between said cylinders whereby the crosshead may be reciprocatecl.

ERIC OLLE SCHJOLIN. 

